This invention relates to filters and has particular, but not exclusive, reference to bonded metal filter assemblies.
Filter elements for removing contaminants from a stream of liquid are well known. Filter elements for removing contaminants from a stream of gas are also well known. Essentially such filter elements comprise a structure which is porous to the carrying medium either liquid or gas, but which can remove contaminants particles from the carrying medium. Numerous materials have been proposed and used for the filter element including paper, plastics, wire mesh, and bonded structure of particles to form porous metal or porous ceramic material.
Some filter elements are capable of holding only small quantities of contaminants without becoming blocked. For some duties however it is required that the filter element be able to hold large quantities of contaminants and still continue to operate. Particularly for aircraft applications it is important that the filters should be able to hold a large quantity of contaminant, so that the filter element need be replaced only infrequently.